Well logging water saturation calculation method, device, equipment and medium

Abstract

The invention discloses a well logging water saturation calculation method and device, equipment and a medium, and relates to the technical field of oil and gas field exploration and development geological research, and the method comprises the steps: preprocessing a well logging curve of a crack and pore composite compact sandstone reservoir, and calculating the parameter information of a crack according to the processed curve; correcting the deep lateral resistivity value in the processed curve to obtain a corrected resistivity value; calculating a target exchange coefficient and a resistance increase rate of the rock core; determining a logging cementation index according to the parameter information of the fracture and the target exchange coefficient, dividing reservoir types, and fitting the core water saturation and the resistance increase rate of different reservoir types to obtain fitting results; obtaining a logging saturation index and a logging lithologic coefficient according to an Archie formula and a fitting result, and determining the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index and the logging lithologic coefficient. And the logging water saturation can be accurately calculated.

Description

Technical Field

[0001] The present invention relates to the technical field of geological research in oil and gas field exploration and development, and particularly relates to a method, device, equipment and medium for calculating logging water saturation. Background Art

[0002] Tight sandstone gas reservoirs are important unconventional gas reservoirs globally. The accurate evaluation of the water saturation of their reservoirs is crucial for reserve calculation and production capacity prediction. However, the traditional Archie formula has poor applicability in unconventional reservoirs such as tight sandstone, mainly because such reservoirs have characteristics such as poor physical properties, strong heterogeneity, diverse pore types, and complex pore structures, resulting in the emergence of the "non-Archie" phenomenon. To solve this problem, researchers have proposed various methods, such as dual-porosity models, triple-porosity medium conductivity models, models based on the theory of rock conductivity efficiency, and digital core technology. However, existing calculation methods are mainly based on homogeneous media or simple dual-medium models, and fail to fully consider the interaction relationship between fractures and different types of pore structures, resulting in a large deviation between the calculation results and the actual situation. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method, device, equipment and medium for calculating logging water saturation, which can fully consider the complex interaction relationship between fractures and different types of pore structures, effectively quantify the influence of fractures on the pore structure of the reservoir, and thus more accurately describe the actual situation of the reservoir. The calculation accuracy of water saturation is improved, and a solid foundation is also provided for more accurate reserve assessment and production capacity prediction. The specific solutions are as follows: In the first aspect, the present application discloses a method for calculating logging water saturation, including: Preprocessing the logging curves of a fractured and porous tight sandstone reservoir to obtain corresponding processed curves, and calculating the parameter information of fractures according to the processed curves; the parameter information includes fracture trend, fracture dip angle, fracture length, fracture width, fracture density, and fracture porosity; Using the parameter information of the fractures to correct the deep lateral resistivity value in the processed curves to obtain a corrected resistivity value; Calculating the target exchange coefficient and the resistance increase rate of the core based on the core of the fractured and porous tight sandstone reservoir; the target exchange coefficient is the exchange coefficient for fluid exchange between fractures and the matrix; Determining the logging cementation index according to the parameter information of the fractures and the target exchange coefficient, and using the target exchange coefficient to divide the reservoir types, and respectively fitting the core water saturation and the resistance increase rate of different reservoir types to obtain corresponding fitting results;

[0004] Obtain the logging saturation index and the logging lithology coefficient according to Archie's formula and the fitting result, and determine the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient.

[0005] Optionally, the preprocessing of the logging curves of the fractured and porous tight sandstone reservoir to obtain the corresponding processed curves includes: Perform offset correction on the logging curves using the core of the fractured and porous tight sandstone reservoir to obtain the corrected curves; the logging curves include any one or a combination of natural gamma logging curves, acoustic time difference logging curves, deep lateral resistivity logging curves, shallow lateral resistivity logging curves, compensated neutron porosity logging curves, and formation microresistivity scanning imaging logging curves; Perform visual inspection on the corrected curves to remove the incorrect data or spikes in the corrected curves to obtain the curves after removal; Process the outliers and / or missing values in the data of the curves after removal to obtain the initially processed curves; Convert the data of the initially processed curves with different orders of magnitude sequences into the same order of magnitude sequences conforming to the standard normal distribution through Z-score standardization to obtain the processed curves.

[0006] Optionally, the calculation of the parameter information of the fractures based on the processed curves includes: Perform denoising processing on the formation microresistivity scanning imaging logging curves to obtain the curves after denoising; Enhance the display effect of the fractures in the curves after denoising based on image enhancement technology to obtain the enhanced curves; Identify the fractures based on the enhanced curves, fit sine curves to the identified fractures through Hough transform to obtain several corresponding sine function curves, and calculate the parameter information of the fractures according to the sine function curves.

[0007] Optionally, the correction of the deep lateral resistivity value in the processed curves using the parameter information of the fractures to obtain the corrected resistivity value includes: Measure the current flowing through the core of the porous tight sandstone reservoir; Determine the first product between the current and the cross-sectional area of the core, and determine the second product between the distance between the parallel plate electrodes and the voltage at both ends of the core; Determine the core resistivity according to the ratio of the second product to the first product; Determine the depth of the core of the fractured and porous tight sandstone reservoir to determine the deep lateral resistivity value in the corresponding logging curves at the depth; Obtain the calculation formula for the core resistivity and the deep lateral resistivity value based on multiple linear regression to calculate the parameter information of the fracture; Use the resistivity value correction formula to correct the deep lateral resistivity value based on the calculation formula to obtain the corrected resistivity value; the resistivity value correction formula is: ; Wherein, is the corrected resistivity value; is the deep lateral resistivity value; is the fracture dip angle; is the fracture length; is the fracture width; is the fracture porosity; c, d, h, f, g are multiple fitting coefficients.

[0008] Optionally, the calculation of the target exchange coefficient and the resistance increase rate of the core based on the core of the fracture and pore composite tight sandstone reservoir includes: Carry out an imbibition experiment on the core of the fracture and pore composite tight sandstone reservoir to obtain measurement data; the measurement data includes the total core porosity, core permeability, imbibition volume, imbibition time, contact area, and capillary pressure; Perform an outlier rejection operation and a temperature correction operation on the measurement data to obtain the corresponding processed data; Calculate the target exchange coefficient based on the processed data according to the target exchange coefficient determination formula; the target exchange coefficient determination formula is: ; Wherein, F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, t is the imbibition time, is the capillary pressure, k is the permeability, and n is the total porosity; Carry out a rock electricity experiment on the core of the fracture and pore composite tight sandstone reservoir to obtain the experimentally determined rock water saturation, experimentally determined saturation index, and experimentally determined lithology coefficient; Determine the operation result with the experimentally determined rock water saturation as the base and the experimentally determined saturation index as the exponent; Determine the resistance increase rate of the core according to the ratio of the experimentally determined lithology coefficient to the operation result.

[0009] Optionally, the determination of the logging cementation index according to the parameter information of the fracture and the target exchange coefficient includes: The logging cementation index determination formula determines the logging cementation index according to the parameter information of the fracture and the target exchange coefficient; the logging cementation index is: ; where is the logging cementation index; is the total core porosity; is the corrected resistivity value; F is the target exchange coefficient; AC is the acoustic transit time logging curve value in the logging curve; K is the core permeability; GR is the natural gamma logging curve value in the logging curve; is the regression coefficient.

[0010] Optionally, the determination of the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient includes: Determining the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient through the logging water saturation determination formula; the logging water saturation determination formula is: ; where is the logging water saturation; is the logging cementation index; is the corrected resistivity value; is the total core porosity; is the formation water resistivity; is the logging lithology coefficient; is the logging saturation index.

[0011] In a second aspect, the present application discloses a logging water saturation calculation device, including: A parameter information calculation module, configured to preprocess the logging curves of the fractured and porous composite tight sandstone reservoir, obtain corresponding processed curves, and calculate the parameter information of the fractures according to the processed curves; the parameter information includes fracture dip, fracture inclination, fracture length, fracture width, fracture density, and fracture porosity; A resistivity value correction module, configured to correct the deep lateral resistivity value in the processed curve by using the parameter information of the fracture to obtain a corrected resistivity value; A calculation module, configured to calculate the target exchange coefficient and the resistance increase rate of the core based on the core of the fractured and porous composite tight sandstone reservoir; the target exchange coefficient is the exchange coefficient for fluid exchange between the fracture and the matrix; A fitting module, configured to determine a logging cementation index according to the parameter information of the fracture and the target exchange coefficient, classify reservoir types by using the target exchange coefficient, respectively fit the core water saturation and the resistivity increase rate of different reservoir types, and obtain corresponding fitting results; A logging water saturation determination module, configured to obtain a logging saturation index and a logging lithology coefficient according to Archie's formula and the fitting results, and determine the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient.

[0012] In a third aspect, the present application discloses an electronic device, including: A memory, configured to store a computer program; A processor, configured to execute the computer program to implement the logging water saturation calculation method as described above.

[0013] In a fourth aspect, the present application discloses a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the logging water saturation calculation method as described above is implemented.

[0014] The present application first preprocesses logging curves of a fractured and porous tight sandstone reservoir to obtain corresponding processed curves, and calculates parameter information of fractures according to the processed curves; the parameter information includes fracture dip direction, fracture dip angle, fracture length, fracture width, fracture density, and fracture porosity; corrects the deep lateral resistivity value in the processed curves by using the parameter information of the fractures to obtain a corrected resistivity value; calculates a target exchange coefficient and the resistivity increase rate of the core based on the core of the fractured and porous tight sandstone reservoir; the target exchange coefficient is an exchange coefficient for fluid exchange between fractures and the matrix; determines a logging cementation index according to the parameter information of the fractures and the target exchange coefficient, classifies reservoir types by using the target exchange coefficient, respectively fits the core water saturation and the resistivity increase rate of different reservoir types, and obtains corresponding fitting results; obtains a logging saturation index and a logging lithology coefficient according to Archie's formula and the fitting results, and determines the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient. It can be seen that by introducing the exchange coefficient for fluid exchange between fractures and the matrix, and through comprehensive analysis of logging curves, formation micro-resistivity scanning imaging, and core experiment data, the present application effectively quantifies the influence of fractures on reservoir structure, optimizes resistivity measurement and parameter calculation methods. By comprehensively considering the influence of fractures on reservoir structure, the problem of poor applicability of the traditional Archie's formula in unconventional reservoirs is effectively solved, and the accuracy of water saturation calculation is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0016] Figure 1 It is a flowchart of a method for calculating logging water saturation disclosed in the present application; Figure 2 It is a schematic diagram of comprehensive fracture characterization disclosed in the present application; Figure 3 It is a schematic diagram of the calculation result of optimizing the logging cementation index by multiple regression disclosed in the present application; Figure 4 It is a schematic diagram of the structure of a device for calculating logging water saturation disclosed in the present application; Figure 5 It is a structural diagram of an electronic device disclosed in the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0018] The existing calculation methods are mainly based on homogeneous media or simple dual-porosity models, and fail to fully consider the interaction relationship between fractures and different types of pore structures, resulting in a large deviation between the calculation results and the actual situation. To solve the above technical problems, the present application discloses a method, device, equipment and medium for calculating logging water saturation, which can fully consider the complex interaction relationship between fractures and different types of pore structures, effectively quantify the influence of fractures on the pore structure of the reservoir, and thus more accurately describe the actual situation of the reservoir. It improves the calculation accuracy of water saturation and also provides a solid foundation for more accurate reserve evaluation and production capacity prediction.

[0019] See Figure 1 As shown, an embodiment of the present invention discloses a method for calculating logging water saturation, including: Step S11: Preprocess the logging curves of the fractured and porous tight sandstone reservoir to obtain the corresponding processed curves, and calculate the parameter information of the fractures according to the processed curves; the parameter information includes fracture trend, fracture dip angle, fracture length, fracture width, fracture density and fracture porosity.

[0020] In this embodiment, due to geological factors and the influence of logging instruments, there is a depth offset in the logging curves. At the same time, there are differences in the same logging data range for different wells, which will affect the subsequent identification accuracy. In order to eliminate the influence of the logging instruments themselves on the logging data and ensure the reliability of the data, it is necessary to preprocess the logging curve data. First, obtain the core and logging curve data of the fractured and porous tight sandstone reservoir; then use the core of the fractured and porous tight sandstone reservoir to perform offset correction on the logging curve to obtain the corrected curve; the logging curve includes any one or a combination of several of the natural gamma logging curve (GR), acoustic time difference logging curve (AC), deep lateral resistivity logging curve (RD), shallow lateral resistivity logging curve (RS), compensated neutron porosity logging curve (CNL), and formation microresistivity scanning imaging logging curve (FMI); perform visual inspection on the corrected curve to remove the incorrect data or spikes in the corrected curve to obtain the curve after removal; process the outliers and / or missing values in the data of the curve after removal to obtain the initially processed curve; convert the data of the initially processed curve with different orders of magnitude into the same order of magnitude sequence that conforms to the standard normal distribution through Z-score standardization to obtain the processed curve.

[0021] After preprocessing the logging curve, use the formation microresistivity scanning imaging logging data in the logging curve to identify fractures and calculate the parameter information of the fractures. Among them, the parameter information includes fracture trend, fracture dip , fracture length , fracture width , fracture density and fracture porosity , as Figure 2 shown. Denoise the formation microresistivity scanning imaging logging curve to remove the clutter signals caused by factors such as instrument noise and wellbore interference, and improve the signal-to-noise ratio of the data; enhance the display effect of fractures in the denoised curve based on image enhancement techniques such as contrast adjustment and filtering to obtain the enhanced curve; use the enhanced formation microresistivity scanning imaging logging data (enhanced curve) to complete the identification of fracture morphology to obtain the identified fractures; through the method of Hough transform, fit each identified fracture with a sine curve, convert it into multiple sine function curves, and calculate the fracture parameter information according to the sine function curves. Among them, the fracture porosity is calculated by the formula: ; where, is the fracture density (number of fractures per meter); is the average fracture width per meter; is the average crack length per meter, and V is the core volume per meter.

[0022] Step S12: Use the parameter information of the cracks to correct the deep lateral resistivity value in the processed curve to obtain the corrected resistivity value.

[0023] In this embodiment, the parameter information of the cracks is used to correct the deep lateral resistivity value in the preprocessed logging curve. For the fractured and porous tight sandstone reservoir, the reservoir fractures are relatively developed. When formation water with a certain salinity or low-resistivity liquids such as drilling mud and mud filtrate invade and fill the fractures and pores, it will cause the deep lateral resistivity value in the logging curve to decrease significantly, resulting in a large error from the resistivity of the actual formation. Therefore, it is necessary to correct the deep lateral resistivity value in the logging curve of the fractured and porous tight sandstone reservoir. Specifically, place the core of the fractured and porous tight sandstone reservoir between a pair of parallel plate electrodes with a constant voltage, measure the magnitude of the current flowing through the core, and calculate the true core resistivity , and its calculation formula is: ; where U is the voltage across the core, L is the distance between the electrodes, I is the current flowing through the core, and O is the cross-sectional area of the core.

[0024] Read the core depth of the fractured and porous tight sandstone reservoir to obtain the deep lateral resistivity value in the logging curve at the corresponding depth , and use the method of multiple linear regression to obtain the calculation formula of the deep lateral resistivity value and the true core resistivity with respect to the parameter information of the cracks. The formula is: ; where is the deep lateral resistivity value; is the crack dip angle; is the crack length; is the crack width; is the crack porosity; c, d, h, f, g are multiple fitting coefficients.

[0025] Finally, use the multiple linear regression formula to correct the deep lateral resistivity value in the preprocessed logging curve to obtain the corrected resistivity value . That is, use the resistivity value correction formula to correct the deep lateral resistivity value based on the calculation formula to obtain the corrected resistivity value. ; The resistivity correction formula is: ; in, is the corrected resistivity value; is the deep lateral resistivity value; is the crack inclination; is the crack length; is the crack width; is the fracture porosity; c, d, h, f, g are the multivariate fitting coefficients.

[0026] In this way, the present application effectively reduces the measurement error caused by the low resistivity fluid filling the fracture by considering the fracture parameter information.

[0027] Step S13, calculating a target exchange coefficient and a resistivity increase rate of the core based on the core of the fracture-pore composite tight sandstone reservoir; the target exchange coefficient is an exchange coefficient for fluid exchange between the fracture and the matrix.

[0028] In this embodiment, the core of the composite tight sandstone reservoir with fractures and pores is first used to conduct an imbibition experiment to calculate the fracture-matrix fluid exchange coefficient F and characterize the fluid exchange at different spatial scales. Specifically, the sample is first pre-treated, the cylindrical core sample is cleaned, and then The samples were dried to constant weight, and basic parameters such as dry weight and size were measured and recorded. The temperature and relative humidity of the experimental environment were kept stable, and the total porosity of the core of the composite tight sandstone reservoir with fractures and pores was measured using the helium method. The simulated formation water was prepared according to the density, viscosity and water type of the formation water in the study area; the experimental environment temperature and relative humidity were kept stable, the sample was suspended under the balance and kept 1-3mm away from the liquid surface, and the imbibition volume Q, imbibition time t, contact area B and capillary pressure were recorded at intervals of 30 seconds every 0-2 hours, every 2 minutes every 2-5 hours, and every 5 minutes after 5 hours. The data are processed until the imbibition is stable. The measured data are subjected to outlier elimination and temperature correction, and the fracture-matrix fluid exchange coefficient F is calculated, that is, the target exchange coefficient is calculated based on the processed data according to the target exchange coefficient determination formula; the target exchange coefficient determination formula is: ; Wherein, F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, t is the imbibition time, is the capillary pressure, k is the permeability, and n is the total porosity.

[0029] Note that each set of the above experiments needs to be measured repeatedly three times or more to ensure data reliability.

[0030] After that, rock-electrical experiments are carried out using the cores of the fractured and porous composite tight sandstone reservoir to obtain the resistivity increase rate and formation factor of all core samples. Rock-electrical experiments are carried out on the cores of the fractured and porous composite tight sandstone reservoir to obtain the experimentally determined rock water saturation, experimentally determined saturation exponent, and experimentally determined lithology coefficient; determine the operation result with the experimentally determined rock water saturation as the base number and the experimentally determined saturation exponent as the exponent; determine the resistivity increase rate of the core according to the ratio of the experimentally determined lithology coefficient to the operation result. More specifically, the cores of the fractured and porous composite tight sandstone reservoir are washed with oil and salt by the solution extraction method, and then dried to a constant weight at 105 °C, and the dry weight and resistivity of the cores are measured. Formation water is configured, and a simulated formation water sample is configured according to the salinity and water type of the formation water in the study area, and the resistivity of the formation water is measured. Then, apply a pressure of 30 Mpa, soak the treated core with the simulated formation water sample for more than 24 hours, and weigh the wet weight of the core with an electronic balance after the soaking treatment. At a constant pressure and temperature, measure the resistivity of the core when it is 100% water-saturated with a standard resistance detection system. Press kerosene into the soaked core with a micro-pump, determine the amount of water discharged from the core with a metering tube, so as to determine the water saturation of the core, and measure its corresponding resistance at the same time. Each time the water saturation of the core changes, measure the resistance of the core once until no water is discharged from the core; the electrical parameters can be calculated according to Archie's formula, where: ; ; where H is the formation factor; is the resistivity of the formation water; is the measured resistivity of the oil and gas-bearing core; is the experimentally determined lithology coefficient; is the total porosity of the core; is the experimentally determined cementation exponent; E is the resistivity increase rate; is the experimentally determined rock water saturation; is the experimentally determined saturation exponent.

[0031] Step S14: Determine the logging cementation exponent according to the parameter information of the fracture and the target exchange coefficient, divide the reservoir type by using the target exchange coefficient, and respectively fit the water saturation and the resistivity increase rate of the cores of different reservoir types to obtain the corresponding fitting results.

[0032] In this embodiment, the logging cementation index is determined by a logging cementation index determination formula according to the parameter information of the fracture and the target exchange coefficient; the logging cementation index is: ; Wherein, is the logging cementation index; is the total core porosity; is the corrected resistivity value; F is the target exchange coefficient; AC is the acoustic travel time logging curve value in the logging curve; K is the core permeability; GR is the natural gamma logging curve value in the logging curve; is the regression coefficient.

[0033] Specifically, using the parameter information of the fracture and the fracture-matrix fluid exchange coefficient F, a multiple stepwise regression algorithm is used to calculate the logging cementation index . The specific implementation steps are as follows: Let a = 1 to obtain the experimental cementation index of all samples . The characteristic of this method is that all pore structure information is concentrated on the cementation index. In this way, the calculated cementation index can not only reflect the pore structure but also be convenient for selection when processing well data; perform core position correction on the sampling depths of all samples in the study area; statistically analyze the correlation between the experimental cementation index m1 and the logging curve, porosity, permeability, and the fracture-matrix fluid exchange coefficient F, and remove the parameters with a correlation coefficient greater than 0.5 between the two to avoid the problem of multicollinearity; through the method of multiple stepwise regression, select the sensitive parameters that have a significant impact on the logging cementation index from the remaining parameters. The sensitive parameters refer to the variables that have a significant impact on the logging cementation index . These variables are selected as the input features of the formula during the multiple stepwise regression process; evaluate the actual application effect of the formula, calculate the logging cementation index by the model and compare it with the experimental cementation index . As shown in Figure 3 , if the absolute coefficient is greater than 0.8, the model is output. If the absolute coefficient is less than the threshold, the model is re-established; output the explanatory formula established by the multiple stepwise regression algorithm of the logging cementation index . Its normalized standard calculation formula is: ; It should be noted that the actual sensitive parameters need to be determined according to specific data and the results of multiple stepwise regression analysis. The parameters listed above are based on the information usually included in geological and logging data, and may be different in actual applications.

[0034] After that, the fracture-matrix fluid exchange coefficient F is used to divide different reservoir types, and the relationship between core water saturation and resistivity increase coefficient is fitted for different reservoir types respectively to obtain the corresponding fitting results. The reservoir types are divided into three categories by the fracture-matrix fluid exchange coefficient F: fracture-dominated type, intermediate composite type, and pore-dominated type, representing different degrees of influence of fractures. In a specific embodiment, the fitting formula for the fracture-dominated type is: ; the fitting formula for the intermediate composite type is: ; the fitting formula for the pore-dominated type is: .

[0035] It can be seen that in this application, the calculation of the logging cementation index is optimized through a multiple stepwise regression model, and the reservoir types are divided according to the fracture-matrix fluid exchange coefficient, and the logging saturation index and lithology coefficient are determined respectively. This parameter optimization method significantly improves the accuracy of resistivity measurement and related parameter calculation, laying a more reliable data foundation for subsequent water saturation calculation.

[0036] Step S15: Obtain the logging saturation index and the logging lithology coefficient according to Archie's formula and the fitting results, and determine the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient.

[0037] In this embodiment, the corresponding logging saturation index and the logging lithology coefficient are obtained respectively through the formula of the resistivity increase coefficient in Archie's formula in the above steps and the fitting results. Then, the logging water saturation is determined based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient through the logging water saturation determination formula; the logging water saturation determination formula is: ; where is the logging water saturation; is the logging cementation index; is the corrected resistivity value; is the total core porosity; is the formation water resistivity; is the logging lithology coefficient; is the logging saturation index.

[0038] In a specific embodiment, the final logging water saturation calculation formula is: ; By comparing the water saturation values measured from actual cores, the logging water saturation model for fractured and porous tight sandstone reservoirs proposed in the present invention has smaller relative and absolute errors compared to traditional methods, and has better applicability for dual-porosity reservoirs compared to the Archie formula method, with the calculated average error reduced by 44.72%, as shown in Table 1: Table 1

[0039] It can be seen that this application not only uses conventional logging curve data, but also fully utilizes various data sources such as core experiment data and formation micro-resistivity scanning imaging logging data. Through comprehensive analysis and processing of these data, including preprocessing of logging curves, fracture identification and parameter extraction, imbibition experiments, petrophysical experiments, etc., the present invention has established a more comprehensive and accurate water saturation calculation model. This method of integrating multi-source data greatly improves the applicability and accuracy of the model, enabling it to better cope with complex geological conditions.

[0040] In summary, this application first preprocesses the logging curves of fractured and porous tight sandstone reservoirs to obtain corresponding processed curves, and calculates the parameter information of fractures based on the processed curves; the parameter information includes fracture dip direction, fracture dip angle, fracture length, fracture width, fracture density, and fracture porosity; uses the parameter information of the fractures to correct the deep lateral resistivity value in the processed curves to obtain the corrected resistivity value; calculates the target exchange coefficient and the resistance increase rate of the core based on the core of the fractured and porous tight sandstone reservoir; the target exchange coefficient is the exchange coefficient for fluid exchange between fractures and the matrix; determines the logging cementation index according to the parameter information of the fractures and the target exchange coefficient, and classifies the reservoir types using the target exchange coefficient, and respectively fits the core water saturation and the resistance increase rate of different reservoir types to obtain corresponding fitting results; obtains the logging saturation index and the logging lithology coefficient according to Archie's formula and the fitting results, and determines the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient. It can be seen that this application effectively quantifies the influence of fractures on the reservoir structure and optimizes the resistivity measurement and parameter calculation methods by introducing the exchange coefficient for fluid exchange between fractures and the matrix. By comprehensively considering the influence of fractures on the reservoir structure, it effectively solves the problem of poor applicability of the traditional Archie formula in unconventional reservoirs and improves the accuracy of water saturation calculation.

[0041] See Figure 4 As shown, an embodiment of the present invention discloses a logging water saturation calculation device, including: A parameter information calculation module 11 is configured to preprocess logging curves of a fractured and porous tight sandstone reservoir to obtain corresponding processed curves, and calculate parameter information of fractures according to the processed curves; the parameter information includes fracture trend, fracture dip angle, fracture length, fracture width, fracture density, and fracture porosity; A resistivity value correction module 12 is configured to correct the deep lateral resistivity value in the processed curves by using the parameter information of the fractures to obtain a corrected resistivity value; A calculation module 13 is configured to calculate a target exchange coefficient and a resistance increase rate of the core based on the core of the fractured and porous tight sandstone reservoir; the target exchange coefficient is an exchange coefficient for fluid exchange between fractures and the matrix; A fitting module 14 is configured to determine a logging cementation index according to the parameter information of the fractures and the target exchange coefficient, divide reservoir types by using the target exchange coefficient, and respectively fit the water saturation and the resistance increase rate of cores of different reservoir types to obtain corresponding fitting results; A logging water saturation determination module 15 is configured to obtain a logging saturation index and a logging lithology coefficient according to Archie's formula and the fitting results, and determine a logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient.

[0042] It can be seen that by introducing an exchange coefficient for fluid exchange between fractures and the matrix, and through comprehensive analysis of logging curves, formation micro-resistivity scanning imaging, and core experiment data, the present application effectively quantifies the influence of fractures on the reservoir structure, optimizes resistivity measurement and parameter calculation methods. By comprehensively considering the influence of fractures on the reservoir structure, the problem of poor applicability of the traditional Archie's formula in unconventional reservoirs is effectively solved, and the accuracy of water saturation calculation is improved.

[0043] In some specific embodiments, the parameter information calculation module 11 may specifically be configured to perform offset correction on the logging curves by using the core of the fractured and porous tight sandstone reservoir to obtain corrected curves; the logging curves include any one or a combination of a natural gamma logging curve, an acoustic travel time logging curve, a deep lateral resistivity logging curve, a shallow lateral resistivity logging curve, a compensated neutron porosity logging curve, and a formation microresistivity scanning imaging logging curve; perform visual inspection on the corrected curves to remove the incorrect data or spikes in the corrected curves to obtain the curves after removal; process the outliers and / or missing values in the data of the curves after removal to obtain the initially processed curves; convert the data of the initially processed curves with different orders of magnitude into the same order of magnitude sequence conforming to the standard normal distribution through Z-score standardization to obtain the processed curves.

[0044] In some specific embodiments, the parameter information calculation module 11 may specifically be configured to perform denoising processing on the formation microresistivity scanning imaging logging curve to obtain the denoised curve; enhance the display effect of the fractures in the denoised curve based on image enhancement technology to obtain the enhanced curve; identify the fractures based on the enhanced curve, and perform sine curve fitting on each identified fracture through the Hough transform to obtain a number of corresponding sine function curves, and calculate the parameter information of the fractures according to the sine function curves.

[0045] In some specific embodiments, the resistivity value correction module 12 may specifically be configured to measure the current flowing through the core of the porous tight sandstone reservoir; determine the first product between the current and the cross-sectional area of the core, and determine the second product between the distance between the parallel plate electrodes and the voltage at both ends of the core; determine the core resistivity according to the ratio of the second product to the first product; determine the depth of the core of the fractured and porous tight sandstone reservoir to determine the deep lateral resistivity value in the logging curve corresponding to the depth; obtain the calculation formula for calculating the parameter information of the fractures by using the core resistivity and the deep lateral resistivity value based on multiple linear regression; correct the deep lateral resistivity value based on the calculation formula by using the resistivity value correction formula to obtain the corrected resistivity value; the resistivity value correction formula is: ; Wherein, is the corrected resistivity value; is the deep lateral resistivity value; is the fracture dip angle; is the fracture length; is the fracture width; is the fracture porosity; c, d, h, f, g are multiple fitting coefficients.

[0046] In some specific embodiments, the calculation module 13 may be specifically configured to perform an imbibition experiment on the core of the fractured and porous composite tight sandstone reservoir to obtain measurement data; the measurement data includes the total core porosity, core permeability, imbibition volume, imbibition time, contact area, and capillary pressure; perform an outlier rejection operation and a temperature correction operation on the measurement data to obtain corresponding processed data; calculate a target exchange coefficient based on the processed data according to the target exchange coefficient determination formula; the target exchange coefficient determination formula is: ; where F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, t is the imbibition time, is the capillary pressure, k is the permeability, and n is the total porosity; Perform an electro-formation experiment on the core of the fractured and porous composite tight sandstone reservoir to obtain the experimentally determined rock water saturation, experimentally determined saturation index, and experimentally determined lithology coefficient; determine the operation result with the experimentally determined rock water saturation as the base and the experimentally determined saturation index as the exponent; determine the resistance increase rate of the core according to the ratio of the experimentally determined lithology coefficient to the operation result.

[0047] In some specific embodiments, the fitting module 14 may be specifically configured to determine the logging cementation index according to the parameter information of the fracture and the target exchange coefficient through the logging cementation index determination formula; the logging cementation index is: ; where, is the logging cementation index; is the total core porosity; is the corrected resistivity value; F is the target exchange coefficient; AC is the acoustic transit time logging curve value in the logging curve; K is the core permeability; GR is the natural gamma logging curve value in the logging curve; is the regression coefficient.

[0048] In some specific embodiments, the logging water saturation determination module 15 may be specifically configured to determine the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient through the logging water saturation determination formula; the logging water saturation determination formula is: ; where, is the logging water saturation; is the logging cementation index; is the corrected resistivity value; is the total porosity of the core; is the resistivity of formation water; is the logging lithology coefficient; is the logging saturation index.

[0049] Furthermore, the embodiment of the present application also discloses an electronic device, Figure 5 is a structural diagram of an electronic device 20 shown according to an exemplary embodiment, and the content in the figure should not be considered as any limitation to the scope of use of the present application.

[0050] Figure 5 is a schematic structural diagram of an electronic device 20 provided by an embodiment of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. Among them, the memory 22 is used to store a computer program, and the computer program is loaded and executed by the processor 21 to implement the relevant steps in the logging water saturation calculation method disclosed in any of the foregoing embodiments. In addition, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0051] In this embodiment, the power supply 23 is used to provide operating voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and external devices, and the communication protocol it follows is any communication protocol applicable to the technical solution of the present application, and no specific limitation is imposed on it here; the input / output interface 25 is used to obtain external input data or output data to the outside, and the specific interface type can be selected according to specific application needs, and no specific limitation is made here.

[0052] In addition, as a carrier for resource storage, the memory 22 may be a read-only memory, a random access memory, a disk, or an optical disc, etc., and the resources stored thereon may include an operating system 221, a computer program 222, etc., and the storage method may be short-term storage or permanent storage.

[0053] Among them, the operating system 221 is used to manage and control each hardware device on the electronic device 20 and the computer program 222, and it may be Windows Server, Netware, Unix, Linux, etc. In addition to the computer program that can be used to complete the logging water saturation calculation method executed by the electronic device 20 disclosed in any of the foregoing embodiments, the computer program 222 may further include a computer program that can be used to complete other specific tasks.

[0054] Furthermore, the present application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, the above-disclosed method for calculating log water saturation is implemented. For the specific steps of this method, reference may be made to the corresponding content disclosed in the foregoing embodiments, and details will not be repeated herein.

[0055] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference may be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and reference may be made to the method part for relevant details.

[0056] Those skilled in the art can further realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been generally described according to their functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0057] The steps of the methods or algorithms described in combination with the embodiments disclosed herein can be directly implemented by hardware, software modules executed by a processor, or a combination of the two. The software modules can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0058] Finally, it should be noted that in this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

[0059] The above has introduced the technical solution provided by this application in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application; at the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A method for calculating logging water saturation, characterized in that Including: Preprocessing the logging curves of a fractured and porous tight sandstone reservoir to obtain corresponding processed curves, and calculating the parameter information of fractures according to the processed curves; the parameter information includes fracture trend, fracture dip angle, fracture length, fracture width, fracture density, and fracture porosity; Correcting the deep lateral resistivity value in the processed curves by using the parameter information of the fractures to obtain a corrected resistivity value; Calculating a target exchange coefficient and the resistivity increase rate of the core based on the core of the fractured and porous tight sandstone reservoir; the target exchange coefficient is the exchange coefficient for fluid exchange between fractures and the matrix; Determining a logging cementation index according to the parameter information of the fractures and the target exchange coefficient, classifying the reservoir types by using the target exchange coefficient, and respectively fitting the water saturation and the resistivity increase rate of the cores of different reservoir types to obtain corresponding fitting results; Obtaining a logging saturation index and a logging lithology coefficient according to Archie's formula and the fitting results, and determining the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient.

2. The logging water saturation calculation method according to claim 1, characterized in that The preprocessing of the logging curves of the fractured and porous tight sandstone reservoir to obtain corresponding processed curves includes: Performing offset correction on the logging curves by using the core of the fractured and porous tight sandstone reservoir to obtain corrected curves; the logging curves include any one or a combination of a natural gamma logging curve, a sonic transit time logging curve, a deep lateral resistivity logging curve, a shallow lateral resistivity logging curve, a compensated neutron porosity logging curve, and a formation microresistivity scanning imaging logging curve; Visually inspecting the corrected curves to remove the incorrect data or spikes in the corrected curves to obtain curves after removal; Processing the outliers and / or missing values in the data of the curves after removal to obtain initially processed curves; Converting the data of the initially processed curves with different orders of magnitude into the same order of magnitude sequence conforming to the standard normal distribution by Z-score standardization to obtain processed curves.

3. The logging water saturation calculation method according to claim 2, wherein The calculating the parameter information of fractures according to the processed curves includes: Performing denoising processing on the formation microresistivity scanning imaging logging curve to obtain a denoised curve; Enhancing the display effect of fractures in the denoised curve based on image enhancement technology to obtain an enhanced curve; Identifying fractures based on the enhanced curve, fitting a sine curve to each identified fracture by using the Hough transform to obtain several corresponding sine function curves, and calculating the parameter information of the fractures according to the sine function curves.

4. The logging water saturation calculation method according to claim 1, characterized in that The correcting the deep lateral resistivity value in the processed curves by using the parameter information of the fractures to obtain a corrected resistivity value includes: Measuring the current flowing through the core of the porous tight sandstone reservoir; Determining a first product between the current and the cross-sectional area of the core, and determining a second product between the distance between the parallel plate electrodes and the voltage at both ends of the core; Determine the core resistivity according to the ratio of the second product to the first product; Determine the depth of the core of the fractured and porous complex tight sandstone reservoir to determine the deep lateral resistivity value in the logging curve corresponding to the depth; Obtain the calculation formula for the core resistivity and the deep lateral resistivity value to calculate the parameter information of the fracture based on multiple linear regression; Correct the deep lateral resistivity value based on the calculation formula by using the resistivity value correction formula to obtain the corrected resistivity value; the resistivity value correction formula is: ； wherein, is the corrected resistivity value; is the deep lateral resistivity value; is the fracture dip angle; is the fracture length; is the fracture width; is the fracture porosity; c, d, h, f, g are multivariate fitting coefficients.

5. The logging water saturation calculation method according to claim 1, characterized in that The calculation of the target exchange coefficient and the resistance increase rate of the core based on the core of the fractured and porous complex tight sandstone reservoir includes: Carry out an imbibition experiment on the core of the fractured and porous complex tight sandstone reservoir to obtain measurement data; the measurement data includes the total core porosity, core permeability, imbibition volume, imbibition time, contact area, and capillary pressure; Perform an outlier rejection operation and a temperature correction operation on the measurement data to obtain the corresponding processed data; Calculate the target exchange coefficient based on the processed data according to the target exchange coefficient determination formula; the target exchange coefficient determination formula is: ； Among them, F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, t is the imbibition time, is the capillary pressure, k is the permeability, and n is the total porosity; Carry out a rock electricity experiment on the core of the fractured and porous complex tight sandstone reservoir to obtain the experimentally determined rock water saturation, experimentally determined saturation index, and experimentally determined lithology coefficient; Determine the operation result with the experimentally determined rock water saturation as the base and the experimentally determined saturation index as the exponent; Determine the resistance increase rate of the core according to the ratio of the experimentally determined lithology coefficient to the operation result.

6. The logging water saturation calculation method according to claim 1, wherein The determination of the logging cementation index according to the parameter information of the fracture and the target exchange coefficient includes: Determine the logging cementation index according to the parameter information of the fracture and the target exchange coefficient through the logging cementation index determination formula; the logging cementation index is: ； Wherein, is the logging cementation index; is the total core porosity; is the corrected resistivity value; F is the target exchange coefficient; AC is the acoustic transit time logging curve value in the logging curve; K is the core permeability; GR is the natural gamma logging curve value in the logging curve; is the regression coefficient.

7. The logging water saturation calculation method according to any one of claims 1 to 6, characterized in that, The determination of the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient includes: Determine the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient through the logging water saturation determination formula; the logging water saturation determination formula is: ； wherein, is the logging water saturation; is the logging cementation index; is the corrected resistivity value; is the total core porosity; is the formation water resistivity; is the logging lithology coefficient; is the logging saturation index.

8. A logging water saturation calculation device, characterized in that, Include: A parameter information calculation module, configured to preprocess the logging curve of the fractured and porous complex tight sandstone reservoir to obtain the corresponding processed curve, and calculate the parameter information of the fracture according to the processed curve; the parameter information includes fracture trend, fracture dip angle, fracture length, fracture width, fracture density, and fracture porosity; A resistivity value correction module, configured to correct the deep lateral resistivity value in the processed curve by using the parameter information of the fracture to obtain the corrected resistivity value; A calculation module, configured to calculate the target exchange coefficient and the resistance increase rate of the core based on the core of the fractured and porous complex tight sandstone reservoir; the target exchange coefficient is the exchange coefficient for fluid exchange between the fracture and the matrix; A fitting module, configured to determine a logging cementation index according to the parameter information of the fracture and the target exchange coefficient, and use the target exchange coefficient to divide reservoir types, respectively fit the core water saturation and the resistivity increase rate of different reservoir types, and obtain corresponding fitting results; A logging water saturation determination module, configured to obtain a logging saturation index and a logging lithology coefficient according to Archie's formula and the fitting results, and determine the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient.

9. An electronic device, characterized in that, Comprising: A memory, configured to store a computer program; A processor, configured to execute the computer program to implement the steps of the logging water saturation calculation method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, A computer program is stored on a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the logging water saturation calculation method according to any one of claims 1 to 7 are implemented.

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